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I like the second one the most.
the works are the gear and they make up a cloud;
the 4th one has the same idea but it gets too cluttered.
I'd add a tad more space between "d" and "W"
perhaps you could try it out with 3 instead of 4 gears which are a bit wider, makes the logo a bit less complex.
the first could work if you adjust the opacity with of the cloud with 5 or 10% down so that the full gear has a more body
